1. Field of the Invention
The present invention relates to a granular composition suitable for use in a tobacco filter or a tobacco pipe.
More particularly, the present invention relates to a granular composition capable of selectively and effectively removing the carcinogenic and deleterious components from tobacco smoke.
2. Description of the Prior Art
Provision of devices for removing the carcinogenic components from tobacco smoke without concomitant deterioration in the taste of the smoke is an urgent social problem. In the past, cigarettes have been joined to cellulose or acetyl-cellulose filter tips or have had charcoal granule filters in attempting to solve this problem. The filters, which were described above, are known to remove tar, nicotine or other deleterious components in tobacco smoke by adsorption. However, proper evaluation of the effectiveness of a tobacco filter should be made by measuring the rate of adsorptive removal of 3,4-benzpyrene, volatile phenol and tar from tobacco smoke since the former two components are the most virulent carcinogen and co-carcinogen, respectively, in tobacco smoke and since tar causes smokers extensively unfavorable effects. A filter material which manifests dual affinity to both 3,4-benzpyrene, a non-polarized molecule, and phenol, a polarized molecule, has not yet been developed.
Previously, the present inventors had observed that bovine milk whey protein and egg white protein preferentially associate with carcinogenic hydrocarbons. A patent application (Japanese Patent Public Disclosure No. 19800/73 and No. 93600/74) was filed for a method for preparing a tobacco filter plug which enables selective removal of carcinogenic hydrocarbons comprising adhesion of bovine milk whey protein, egg white protein or a mixture of these two protein species in a powdered state to a fibrous filter in an amount of 3% of the weight of the fibrous substrate. The removal of carcinogenic hydrocarbons from tobacco smoke was effected by including these protein powders in a tobacco filter. However, this caused a pronounced pressure drop during smoking, since the fine protein powders reduced the cavity space between the filter fibers and consequently impaired the harmony of the smoking taste.
Attempts were made to eliminate this unfavorable effect by employing a filter, containing granules prepared solely from the protein powders (hereinafter referred to as "the protein"). Efforts were devoted to prepare such granules on an industrial scale. This proved to be extremely difficult using conventional granulating devices because of the extraordinary stickiness of the protein when it was mixed with water or compressed for granule formation. Furthermore, the small amount of protein granules, which were prepared manually with much difficulty, exhibited an unexpectedly lower rate of removal of the deleterious components in tobacco smoke. The reason was that the granules prepared from genuine protein possessed smoother peripheral surfaces and the non-specific physical interaction between the granules and the smoke components was inhibited. In such a case, the removal of the smoke components by the genuine protein granules is only effected by specific chemical interaction with the protein.